2003 S40 check engine light reset time?

[martin9586]

I had a check engine light on, ran the code. "thermostat running below normal operating temperature". Change the thermostat and coolant temp sensor.

I cleared the code and ran the car for 170 miles before trying to smog. Took it in and they said the following:

Result: not ready OBII

OBII Monitors not ready: Catalyst.

Does anyone know how many miles it takes before this sensor resets?